fix: don't assume react-native ViewProps declares onFocusCapture, gate check:types in CI

[RuudBurger]

Merging #117 left main failing check:types, which blocks the release job: the changesets action can't push changeset-release/main because the husky pre-push hook runs check:types and it exits 2. No version PR got created and nothing published.

../react-native-lightning/src/exports/View.tsx(31,19): error TS2339:
  Property 'onFocusCapture' does not exist on type 'ViewProps'
Failed: @plextv/react-native-lightning-components#check:types
husky - pre-push script failed (code 2)

The cause: View's CombinedProps reads RNViewProps['onFocusCapture']. react-native-tvos declares that prop on ViewProps (Libraries/Types/CoreEventTypes.d.ts), plain react-native doesn't. The change was written and typechecked against the Plex client, which aliases react-native to react-native-tvos, so it compiled there and not here.

Reads the prop only when it's present. Generic, so the indexed access stays deferred (a non-generic conditional doesn't narrow it and fails with TS2538 instead):

type FocusCaptureOf<P> = 'onFocusCapture' extends keyof P
  ? P['onFocusCapture']
  : never;

Both forks typecheck, and consumers on tvos keep the handler type they had.

Second commit closes the hole that let this through: PR CI ran lint + test but not check:types, so a type error couldn't fail a PR — it only surfaced later as a failed push inside the release job, reading as a git error rather than a type error. check:types now runs on pull requests, and this PR is the first run to exercise it (13/13 packages, ~23s).

Verified against a real install of this repo, not just in the abstract: check:types 13/13, lint 0 errors, test 728 passing across 62 files.